module Restspec
  module Schema
    # The Schema DSL is what should be used inside the `schemas.rb` file.
    # This class is related to the top-level namespace of the DSL.
    class DSL
      def initialize
        self.mixins = {}
      end

      # Generates a schema and sends the schema to an {SingleSchemaDSL}
      # instance for further definitions.
      #
      # @example
      #   schema :book, root: true do
      #     puts self.class # SingleSchemaDSL
      #     puts self.schema.class # Schema
      #   end
      #
      # @param name {Symbol} the schema's name
      # @param options {Hash} a set of options for {Schema#initialize}
      # @param definition A block that will be executed inside the context
      #   of a {SingleSchemaDSL} object.
      def schema(name, options = {}, &definition)
        dsl = SingleSchemaDSL.new(name, options, mixins)
        dsl.instance_eval(&definition)
        Restspec::SchemaStore.store(dsl.schema)
      end

      # Generates a set of calls that can be executed in
      # many schemas with {SingleSchemaDSL#include_attributes}.
      #
      # They are useful to share attributes.
      #
      # @example
      #
      #   mixin :timestamps do
      #     attribute :created_at, date
      #     attribute :updated_at, date
      #   end
      #
      #   schema :book do
      #     include_attributes :timestamps
      #   end
      #
      #   schema :celphones do
      #     include_attributes :timestamps
      #   end
      #
      # @param name {Symbol} the mixin's name
      # @param definition A block that will be executed on demand
      #   in an {SingleSchemaDSL} object's context.
      def mixin(name, &definition)
        mixins[name] = definition
      end

      private

      attr_accessor :mixins
    end

    # The DSL to use inside `schema` and `mixin` blocks of
    # a {DSL} instance block. It defines specific things of a
    # schema or a group of them.
    class SingleSchemaDSL
      include Types::TypeMethods

      # @return {Schema} the current schema
      attr_reader :schema

      def initialize(name, options = {}, mixins = {})
        self.schema = Schema.new(name, options)
        self.mixins = mixins
      end

      # Creates an attribute and saving it into the schema.
      # It uses the same parameters as the {Attribute#initialize} method.
      #
      # @example
      #
      #  schema :books do
      #   attribute :title, string
      #   attribute :created_at, datetime, :for => [:response]
      #  end
      #
      # @param (see Attribute#initialize)
      def attribute(name, type, options = {})
        new_attribute = Attribute.new(name, type, options)
        schema.attributes[name.to_s] = new_attribute
      end

      # Includes a mixin generated by the {DSL#mixin} function
      # into the schema.
      #
      # @example (see DSL#mixin)
      #
      # @param name [Symbol] the mixin name
      def include_attributes(name)
        self.instance_eval &mixins.fetch(name)
      end

      private

      attr_writer :schema
      attr_accessor :mixins
    end
  end
end